The overall goal of this project is to assess the utility of MRI in evaluating the effectiveness of various treatment protocols for brain tumors. Currently investigated treatment consists of intratumoral infusion of murine monoclonal antibody (MAb) which is reactive to a tumor-specific antigen normally only expressed by trophoblasts, embronic and fetal cells. Permanently implanted plastic guide cannulae were positioned stereotaxically 1 mm deep to the skull surface in rats. C-6 glyoma cells were infused into through the implanted guide cannula. The rats were imaged by MRI immediately before the start of the intratumoral treatment and following completion of treatment. Monoclonal antibody treatment was administered through the implanted guide cannula with the help of an osmotic minipump subcutaneously implanted in the rat. We have to date performed post-treatment MRI examinations in antibody treated rats that survived long-term. These MR images in comparison to each rat's pre-treatment MRIs reveal a complete elimination of the tumor. This finding has been confirmed by histology. In contrast, post-treatment MRIs of rats infused with a control substance showed pronounced tumor enlargement. Our studies have shown that MRI can serve as a valuable tool in the assessment of the progression of a brain glioma under various treatment protocols.